1. Field of the Invention
The invention relates to a system for distributing multi-media contents such as image signals, audio signals or HTML pages to clients from a media server, and more particularly to administration of distribution schedule.
2. Description of the Related Art
Administration of distribution schedule is grouped into two groups.
In one of the groups, as suggested in Japanese Unexamined Patent Publication No. 11-215193 (A), a client has schedule information in order to control an order in reproducing contents provided from a plurality of servers.
In the other, as suggested in Japanese Unexamined Patent Publication No. 11-88279 (A), a host server connected to a plurality of servers through a network has schedule information in order to administrate the schedule information.
The present invention relates to schedule administration accomplished by a content transmitter like Japanese Unexamined Patent Publication No. 11-88279 (A).
FIG. 1 is a block diagram of a broadcasting system suggested in Japanese Unexamined Patent Publication No. 11-88279 (A).
In the illustrated broadcasting system, an index server 21 of a distributor, a plurality of information servers 25A to 25D, and a plurality of client terminals 29A and 29B are connected to one another for communication through a network 23.
The index server 21 stores broadcasting schedules 31A and 31B defining a plurality of programs to be broadcast, and a time at which the programs are broadcast for broadcasting channels CH1 and CH2 provided by the distributor, respectively.
Each of the information servers 25A to 25D stores files 33A to 33F of broadcast contents fabricated by content providers.
The index server 21 requests the information servers 25A to 25D having broadcast contents, to broadcast each of the programs at a designated time through a channel in accordance with the broadcasting schedules 31A and 31B of the channels CH1 and CH2.
Specifically, the index server 21 transmits a command indicating that a certain program has to start being broadcasted at a certain time at a certain channel, or that a certain program has to start being broadcasted immediately, and a command indicating that a certain program has to end at a certain time, or that a certain program has to end immediately, to each of the information servers 25A to 25D.
In compliance with a request transmitted from the index server 21, each of the information servers 25A to 25D transmits data stored in the files 33A to 33F, to a designated channel in the network 23 at a designated time. Specifically, when each of the information servers 25A to 25D receives a command to start a program, each of the information servers 25A to 25D reads content data relating to a target program out of the files 33A to 33F, and starts the program at a designated time in a designated channel, in compliance with the command. When each of the information servers 25A to 25D receives a command to end a program, each of the information servers 25A to 25D ends a target program at a designated time in compliance with the command.
Due to the above-mentioned operations of the index server 21 and the information servers 25A to 25D, there are formed multi-media data streams 35A and 35B in the network 23. Each of the multi-media data streams 35A and 35B is comprised of broadcast contents made in accordance with the broadcast schedules 31A and 31B for each of the channels CH1 and CH2, and combined with one another.
The broadcasting system illustrated in FIG. 1 administrates the distribution schedule with a time. Such administration of the distribution schedule is identical with the same having been conventionally conducted in TV broadcasting studio, for instance, and is effective for a service of distributing data stream to a client from a server.
However, it would be necessary to in advance determine a time at which each of contents is to be distributed, in order to administrate a schedule only with a time. In other words, it would not be possible to schedule a content, if a time at which the content is to be distributed is not in advance determined.
For instance, when an event occurs while images or sounds are being distributed, and accordingly, it is desired to switch those images or sounds into other images or sounds, or it is desired to distribute other data together with those images or sounds, the broadcasting system illustrated in FIG. 1 cannot schedule such switching or distribution, if a time at which the event occurs cannot be known in advance.
In these days, there are provided contents in a new distribution form, such as an interactive service system providing a program in which TV broadcasting and a home-page in Internet are linked with each other to thereby make it possible for users to take part in.
In such an interactive service system, when a schedule is to be changed in accordance with results of a questionnaire carried out to users at real-time, it would be almost impossible to administrate a schedule only with a time, since it is not possible to know by what time replies to the questionnaire can be collected, and/or a result of the questionnaire.
It would be possible to administrate a schedule with a time by rewriting schedule data when an event occurs, as usually done in a TV broadcasting studio. However, since it would require much work and take much time to rewrite schedule data, it would be quite difficult or almost impossible to rapidly change a schedule.
Japanese Unexamined Patent Publication No. 5-242208 has suggested a system for revising a multi-media scenario, in which a scenario is described with a network, based on synchronization data obtained at points at which medias are synchronized with one another, and a period of time during which a media is suggested is adjusted by automatically detecting a portion to be adjusted in the scenario.
However, the above-mentioned problems remain unsolved even in the Publication.